Challenge Task 1 of 1 , A delegated click event listener has been attached to the selected ul element, which is stored

Question

can anybody help me with this? I get this error message

Bummer! There was an error with your code: TypeError: 'undefined' is not an object (evaluating 'li.nextElement.className = "highlight"')

The problem

A delegated click event listener has been attached to the selected ul element, which is stored in the variable list. The handler is targeting each button in the list. When any one of the buttons is clicked, a class of highlight should be added to the paragraph element immediately preceding that button inside the parent list item element. Add the code to create this behavior on line 5.

app.js

const list = document.getElementsByTagName('ul')[0];

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
      let p = e.target.parentNode;
      let li = p.parentNode;
          li.childNodes.className = "highlight";
  }
});

index.html

<!DOCTYPE html>
<html>
    <head>
        <title>JavaScript and the DOM</title>
    </head>
    <link rel="stylesheet" href="style.css" />
    <body>
        <section>
            <h1>Making a Webpage Interactive</h1>
            <p>Things to Learn</p>
            <ul>
                <li><p>Element Selection</p><button>Highlight</button></li>
                <li><p>Events</p><button>Highlight</button></li>
                <li><p>Event Listening</p><button>Highlight</button></li>
                <li><p>DOM Traversal</p><button>Highlight</button></li>
            </ul>
        </section>
        <script src="app.js"></script>
    </body>
</html>

Answer 1 · 2018-04-25T07:47:14Z

April 25, 2018 7:47am

Hi Gremyko, try this: Let me know if you have any questions if you don't understand how it works. I am happy to help :).

const list = document.getElementsByTagName('ul')[0];

list.addEventListener('click', function(e) {
  if (e.target.tagName == 'BUTTON') {
    e.target.previousElementSibling.className = 'highlight'
  }
});

Answer 2 · 2018-06-04T23:26:46Z

June 4, 2018 11:26pm

Thanks! Your answer helped me as well.

I cannot quite grasp the concept of the previousElementSibling at the moment.

I mean, in your answer e.target.previousElementSibling isn't it getting the sibling of "ul" because the eventListener is added to the list variable, which is the firt <ul>?

I've watched the video about siblings more than once but still got confused. Ant clarification will be much appreciated!

Thanks!

Victoria

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Gremyko Coleman

Gremyko Coleman

Challenge Task 1 of 1 , A delegated click event listener has been attached to the selected ul element, which is stored

2 Answers

tobiastrinkler

tobiastrinkler

Victoria Loisi

Victoria Loisi